/Engine/Plugins/Editor/GeometryMode/Source/GeometryMode/Classes/GeomModifier_Pen.h
true if the key was handled by this editor mode tool.
virtual bool InputKey ( class [FEditorViewportClient](API\Editor\UnrealEd\FEditorViewportClient) * ViewportClient, [FViewport](API\Runtime\Engine\FViewport) * Viewport, [FKey](API\Runtime\InputCore\FKey) Key, EInputEvent Event )